1. Field of the Invention
The present invention relates to a masking layer made from developable photosensitive resin compositions and adapted for use on a touch panel device, a flat panel display device or a like device. As compared to the conventional masking layers that should be of a darkish color or even a black color, the invention advantageously imparts the device to which the invention is applied with higher versatility in color appearance, while comprising a gray colored sub-layer to effectively maintain or even improve the masking property.
2. Description of the Prior Art
Touch panels have been widely used in a broad variety of consumer electronic products, including mobile phones, digital cameras and satellite navigation devices, as a means to constitute a human-machine interface with improved input efficiency. In the actual practice, a touch panel is typically made transparent and mounted in front of the display screen of an electronic product to constitute a touch screen, through which a user can conveniently perform interactive input operations with respect to the information presented on the display screen. This technology remarkably improves the user friendness of the human-machine interface. A typical touch panel architecture includes a touch sensing member mounted between a top plate and a substrate, and an electric circuitry disposed on the periphery thereof for transmitting touch signals received by the touch sensing member to a signal processing circuit. A conventional process for mounting a touch panel onto a display screen of an electronic product comprises fitting the periphery of the touch panel into a frame and then fixing the resultant frame structure to the front face of the display screen. In addition to holding the touch panel, the frame used in the architecture of this type serves to protect the electric circuitry mounted on the periphery of the touch panel and improve the overall aesthetic appearance of the touch panel architecture.
However, the conventional touch panel architecture described above has been known to result in several disadvantages. For example, the installation of the frame will inevitably cause unevenness on the outer surfaces of the touch panel architecture, thus deteriorating the smooth appearance of the electronic product.
Another conventional touch panel architecture includes a decorative layer attached onto the inner surface of the top glass plate. The decorative layer is shaped into a frame-like configuration and made of deep-colored non-conductive material with a deep color, so as to mask the electrical circuitry disposed beneath the top glass plate. The process for attaching the decorative layer onto the top glass plate is too complicated to achieve a satisfactory productivity.
A still another conventional touch panel architecture includes a side frame screen-printed along the periphery of the cover glass to mask the electrical circuitry disposed beneath the cover glass. The touch panel of this type, however, is constructed by laminating several thin layers together and is therefore complicated in terms of structure. As shown in FIG. 2, the conventional touch panel comprises a cover glass 40, a shielding side frame 41 disposed on the bottom side of the cover glass 40, a touch control module 50 and a display panel 60, with the respective components being laminated together using an optically clear adhesive 70. This architecture is too complicated to be fabricated in an efficient manner and too thick to meet the design trend of lightweight and slimness.
A so-called one glass solution (OGS) was proposed recently, which incorporates the touch sensor and the cover glass in one layer, resulting in a simplified touch panel architecture. In this architecture, two layers of touch sensing electrodes are arranged in orthogonal directions on the bottom side of the cover glass. As a result, fewer laminating steps are needed for fabricating this architecture and high productivity is optimistically forecasted. The touch panels thus produced have the advantages of lightweight, slimness, low sensing resistance due to using only a single sheet of cover glass, high transparency and high touch sensitivity. Despite so, the OGS technology has not been successfully integrated with the conventional screen-printing process, as the latter has been shown to cause imprecise alignment among the laminated layers, leading to a poor productivity.